Means of and apparatus for transmitting messages through submarine and like cables



June 11, 1929. w, s' u H 1.717.017

MEANS OF ND APPARATUS FOR TRANSIITTING MESSAGES THROUGH SUBMARINE AND LIKE CABLES Filed Dec. 30, 1926 2 Sheets-Sheet l INVE N TOR @wmvi A TTORNEY MEANS OF AND APPARATUS FOR TRANSMITTING MESSAGES THROUGH SUBMARINE AND LIKE CABLES Filed Dec. 30, 1926 2 Sheets-Sheet 2 f AVE/770i Patented June 11, 1929 uru'rso STATES.

PATENT OFFICE.

WILLIAM ESTAUGH, or WANISTEAID; ENGLAND.

MEANS OF AND APPARATUS FO-IR TRANSMITTING THROUGH SUBHARINE AND LIKE CABLES.

Application fled Dccember'30, 1926, Serial No. 158,045, and in Great Britain January 15, 1926.

This invention. relates to the construction of cables and the arrangement of apparatus for transmitting and receiving telegraphic and telephonic messages and has for its object improvements whereby retardat on due to electro-sta-tic capacity is minimized or avoided.

It has heretofore been proposed to transmit telegraphic messages through a cable consisting of aninsulated signalling conductor surrounded by an outer insulated conductor, both of which were electrically charged at the receiving end by an earthed source. The transmitting end of the inner signalling conductor was connected through a signalling key to the terminal of the, same sign of an earthed source of electricity of higher potential and the receiving instrument was connected between the receiving end of the said inner conductor and the charging source. VViththis arrangement the two conductorswere normally charged to the same potential at the receiving end but.

owing to resistance and leakage there Was a gradual fall of potential towards'the transmitting end of the outer conductor with the result that the inner conductor was not so completely screened from the earth at that end and electrostatic capacity was estab- 3 lished'between the inner conductor and the 5 stant current at the rcceivingend when no messages are being sent and to increase or decrease the potential of the said current according to Whether the signals transmitted are dots or dashes. a

According to one mode of carrying the present invention into practice three batteries are employed at the transmitting end, one of which is adapted to apply the normal potential to the signalling conductor and two smaller ones each of which is of astrengthequal to the increase and decrease of poten- 65 tial employed for signalling. These two batterics are opposed to each other and are normally connected in series with the main transmitting battery so that the normal potential remains unchanged, when not transmitting.

In order to increase the potential so as to transmit a dot the opposed batteryis short circuited orcut out by a suitable transmitting key and in order to decrease the potential so as to transmita dash the other small battery is similarlyshort circuited or cutout by another suitable transmitting key. I may however adopt any other known means of varying the potential applied to the line.

In order to transmit and receive telephonic messages a telephonic microphone and receiver are substituted for the telegraphic transmitter and receiver, the normal potential conditions may remain the same in both cases.

I will now proceed to more particularly describe my invention with the aid of the accompanying" drawings, in which i Fig. 1 is a diagrammatic drawing showing the improved cable with transmitting and receiving apparatus constructed and arranged according to one mode of carrying outthe present invention,

Fig. 2 is a cross-section through the cable, which consists of an inner conductor a, and an outer conductor 7) separated from each other by insulation 0 and surrounded by an outer layer of insulation 4 and the usual mechanical protection (not shown).

Fig. 3 is a diagram showing analternative method of applying a varying potential tothe line in transmitting signals,

Fig. 4 shows one method of connecting a thermionic valve amplifier across a resistance 95 which is inseries with the signalling conductor at the receiving end,

Fig. is a similar view to Fig. l, in which.

j a transformer is employed instead of a rebe adjusted.

With this arrangement both conductors sist-ance at the receiving end of the signalling conductor, and

Fig. 6 shows an arrangement in which telephonic transmitter and receiver are enrployed.

According to the arrangement shown in Fig. 1, a is the insulated inner signalling conductor and Z) is the insulated outer eonductor which is concentrically disposed around it. The inner conductor a and the outer conductor 7) are connected to the positive pole of the earthod battery. at the 1-0-- ceiving end It through potentiometer which connected across a section or the battery f to enable the potential applied to 7 to be ascertained an electrostatic voltmeter h is connected tolt at the recelving end and a similar voltmeter is connected to it at the transmitting end.

In orderto obtains suitable fall of potential at the sending end of the outer eonductor b it may it' necessary heearthed through a suitable resistance.

At the sending station T the inner conductor a is also connected to the positive pole of an earthed battery .j through potentiometer 0 and also through potentiometersm and 'n: which control the signalling potentials. r Potent-iometer 0' is adjusted to normally 5 apply a predetermined higher potential to the signallingconductor a; so as to produce a constant current through the signalling conductor a and the receiver a at the receiving end.

signal potential.

For the purpose of transmitting signals two opposed batteries 72 and Z of approximately equal value are employed. These are Y provided with potentiometers m and a and are connected in series with the batteryj. Owing to the batteries 7:- and Z being opposed they mutually cancel each other. Po

tentiomet-ers 'm, and a are both adjusted to the desired value for signalling which will be measured on voltmeters (1 and r.

, To transmit a signal, the-section of the The 'electro-static voltmeter 7) is for the purpose of measuring this normal resistance of potentiometer n across which the opposed potential is conducted through the signalling conductor a, is Sl10lll'-Cll'Cllilt34.l by closing the transmitting key 8. This will cause a corresponding rise in the current through the receiver a which will'indicate a dot or a dash as the case may be; In a like manner the closure of the transmitting key t will cause a corresponding reduction in the current through the receiver a by shortcircuiting the section of the resistance of the potentiometer m-across which the assisting potential is conducted through the signalling conductor a. The impedance indicated at e at the receiving endis to compensate tor the impedance of the receiver u.

The application of the higher potential to the signalling conductora will at the transmitting end, cause a corresponding increase in the effective electro-static capacity be-' tween the signalling conductor a and the earth thus the signal potential will be bound between the inner conductor a and the earth. and will discharge itself to earth through the receiver a at the receiving end.

According to'thc arrangement shown in Fig. 3 the two signalling batteries-'76 and are transposed and theclosure ot the transmitting keys 8 and t connects one or other of the signalling batteries 7r: or Z in series with the battery j through their respective potentiometers m and rainstead of short circuiting a section of same as is described and shown in Fig. 1. s

The closure of the transmitting key .9 will completerthecircuit of the battery 7 through the potentiometer a and cause an assisting potential tobe conducted through itto the signalling conductor a which will cause an increasein the normal current flow ing through thereceiver M. In a like man-.

nor the closure of the transmitting key t will cause an equal current of opposing potential to be conducted through the potentiometer m to thesignalling conductor a which will cause a corresponding reduction in the normal current flowing through the receiver a. 7

I may employ" any other know means of applying a varymg signal potential to, the line without departing from thespirit of the present invention.

According to the arrangement shown in- Fig. 4 a thermionic valve employed to do tect and amplify the received signz'ils. A suit able resistance to is interposed between the receiving end of the signalling conductor a and the positive pole of the charging'battery f. The grid 3 of a thermionic valve 1 connected to one end of the resistance on whose opposite extremity is connected to the negative terminal of the filamentQ which is heated by the battery 4'. The plate 5, of the valve is connected'to' one terminal of the receiver a, whose other terminal is connected to the positive pole of the high tension battery 6, and the negative pole of the latter is connected to one side of the filament battery 4. i

The resistance indicated at o, is to compensateforv that of w. 7

Signals passing through the resistance 10 are detected by the grid of the valve and amplified in the plate circuit in the usual known manner.

According to the arrangement shown in Fig. 5 a suitable transformer is employed in the place of the resistance 10 shown in Fig. 4. One end of the primary circuit to of the transformer is connected to the receiving end of the signalling conductor a and its other end is connected to the positive pole ot the charging battery And one end of the secondary circuit 1 is connected to the grid 3 while its opposite extremity is connected to thenegative terminal of the filament 2 oi? the valve 1.

In applying the present invention for the transmission and reception of telephonic signals the normal potential conditions re main the same but instead of the telegraphic transmitter and batteries and the telegraphic receiver described in connection with Figs. 1 to 5 a telephonic transmitter .2 is inserted in series with the signalling conductor a and the signalling battery 7' as shown in Fig. (3. At the receiving end a telephonic receiver a, may be inserted in the place of the telegraphic receiver.

In order to transmit telephonic signals, the potentiometer 0, is adjusted to normally apply a predetermined higher potential to the signalling conductor a, so as to produce a constant current through the signalling conductor a. and the primary circuit a: of the transformer as already described.

One terminal of a telephone receiver 11,

is connected to the plate 5 of the valve 1 and the other terminal is connected to the positive pole of the high tension battery 6, the negative pole of which is connected to one side of the filament battery 4.

The transmitter 2., may be of any known kind either of the electro-magnetic or resist-' ance varying type.

Sound waves acting on the diaphragm of the microphone 2 will cause the normal potential of the current flowing through the signalling conductor a. to vary accordingly.

These current variations in passing through the primary circuit 00 of the transformer will cause to be induced in the secondary circuit 1 ,impulses which will represent the amount ofincrease or decrease inthe said normal current at the transmitting end.

These impulses will be detected by the grid at the thermionic valve and amplified in' the plate circuit of the same in the usual known manner.

I may in some cases employ a transformer of any known design at the transmittingend instead of or in addition to the one described and shown.

Although. I have shown only one arrangement in which a telephonic transmitter and receiver are substituted for the telegraphic ones, a similar substitution may be made in all the arrangements herein described. I may also employ any number of amplifying valve stages of known design to give the desired signal magnification.

I claim:

1. Means andapparatus for transmitting messages through a submarine or other like cable comprising a cable having an insulated inner conductor and an insulated outer conductor both of which are connected at the receiving end toan earthed electrical charging source, an earthed electrical charging source of higher potential connected to the inner conductor at the transmitting end, means of varying the potential applied to said inner conductor at the transmitting end and means of detecting the variations of current or potential in said inner conductor at the receiving end substantially as described.

2. Means and apparatus for transmitting messages through a submarine or other like cable according to claim 1 in which the charging source at the transmitting end comprises an earthed main battery connected in series with the inner conductor through two opposed smaller batteries of equal strength each of which is provided with a shunt across its terminals controlled by a signal key by means of which either can be short circuited so as to vary the potential of the charging source, substantially as described.

3. Means and apparatus for transmitting messages through a submarine or other like cable according to claim 1 in which the charging source at the transmitting end comprises an earthed main battery connected in series with the inner conductorthro'ugh two resistances, and two opposed smaller batteries of equal strength each of which is respectively connected in parallel with one of the said resistances through a signal key by means of which the potential applied to the inner conductor can be' augmented or reduced substantially as described.

4. Means and apparatus for transmitting messages through a submarine or other like cable according to claim 1 in which the receiver is connected between the inner eonductor and the charging source at the receiving end substantially as described.

5. Means and apparatus for transmitting messages through a submarine or other like cable according to claim 1 in which the variations in potential are detected by a ther- .mionic' valve applied to a resistance concuit is connected between the inner conduc- 10 tor and the charging source at the receiving end substantially as described.

In testimony whereof, I have signed my name to this specification at 61 and 62, Chancery Lane, London, W. O. 2, England, 15 this 15th day of December, 1926.

\VILLIAM ESTAUGH. 

